Traction Surface And Methods Therefor

ABSTRACT

Devices and methods are contemplated in which a plurality of microfractures are generated on the surface of an article to so generate a non-abrasive surface having a COF of at least 0.6. Most preferably, the surface is the surface of a transparent polymer and is the surface is structured to allow high-resolution display of an image that is disposed on a surface opposite the surface with the microfractures. Consequently, numerous anti-slip products with such surfaces are contemplated.

This application claims priority to our U.S. provisional patentapplications with Ser. Nos. 61/254766, filed Oct. 26, 2009, and61/354317, filed Jun. 14, 2010.

FIELD OF THE INVENTION

The field of the invention is traction surfaces and devices, uses, andmethods therefor, and especially traction surfaces with high-resolutionimages.

BACKGROUND OF THE INVENTION

Traction of surfaces, and especially of wet surfaces is often criticalto safety in numerous environments, and many devices and methods areknown in the art to increase traction. Most of the known devices andmethods will fall into one

conceptually different classes. The first class can be characterized asdevices having relatively large surface modifications to thereby trap aportion of a foot or to provide a significant curvature of the surfaceto reduce sliding motion. For example, DE 41 27 973 teaches a bath tubmat with large indentations that engage at least a portion (typicallyheel) of a foot. Similarly, U.S. Pat. No. 6,014,779 teaches surfaceswith large rounded nodules and drain channels, and US2008/0216228A1teaches a compressible top layer made from soft foam material withchannels and raised elements to drain water. Similarly, U.S. Pat. No.5,494,729 teaches a substantially non-slip, non-abrasive surface thathas polysulfide coating layer with relatively large solid elastomerparticles.

While such devices and methods typically reduce the incidence ofstanding water, and with that the risk of sliding, grooves or otherwiseshaped recesses will typically lead to puddling of water. Moreover, suchsurfaces are almost entirely unsuitable for most commercial and sportinguses. Still further, traction of such surfaces will decrease when thesurface is wet, and soap or other detergents will often negate allbenefits of such macro-structured surfaces.

The second class can be characterized as devices having relatively smalland abrasive surface modifications. For example, GB 1141073 teachesmultiple enamel layers that fuse to form a friction surface whererefractory granules form an abrasive layer in the final product.Alternatively, sand or other abrasive materials can be added as afriction layer in a polymeric carrier, which may be overlaid with aplastic layer as taught in U.S. Pat. No. 4,625,344 and WO 87/00019.Unfortunately, such devices typically exhibit significant wear and tendto lose friction relatively fast. Worse yet, such surfaces often lead toabrasive injuries, especially where the friction layer is not covered.On the other hand, where the friction layer is covered with a polymerlayer to reduce injury, most of the benefits tend to disappear,especially when the surface is wet.

To overcome difficulties associated with plastic surfaces, a third classof devices employs cloth or other textile materials to increase frictionas, for example, described in U.S. Pat. Nos. 6,353,943 and 6,946,183.While such devices typically have desirable friction characteristicswhen wet, retention of such devices is more difficult. Moreover, suchdevices can often not be retained in wet state for prolonged periods oftime without cleaning as the wet textile materials tend to accumulatemold very quickly.

Alternatively, non-slip materials can be temporarily applied to asurface as described, for example, in WO94/19414 where mixtures of apolymer and a petroleum or synthetic wax or silicone are applied to asurface. To increase retention and friction of the material, one or moretackifier agents can be, especially where water is present. While suchcompositions typically retain their tackiness in the wet state due totheir generally hydrophobic nature, they will often attract soil andother undesirable items, especially over prolonged use. Moreover, suchsurface modification is often not practical, especially in bath tubs,showers, or public places (e.g., deck of a boat or jet ski).

Moreover, and regardless of the manner of increasing traction, all oralmost all of the currently known traction devices fail to provide asimple and cost-effective option to include a decorative finish that isprotected from the user and environment, let alone a customizable finishusing high-resolution photographs or digital image files. Thus, eventhough numerous devices and methods for increasing friction are known inthe art, all or all of them suffer from one or more disadvantages.Consequently, there is still a need to provide improved methods anddevices that are customizable, and have excellent traction, even in wetenvironments.

SUMMARY OF THE INVENTION

The present invention is directed to devices and methods of increasingslip resistance and more particularly to devices and methods in which inat least one surface a plurality of microfractures are generated. Mosttypically, such surfaces are non-abrasive and provide excellent slipresistance as evidenced by multiple tests. Remarkably, surfacesaccording to the inventive subject matter allow for high-resolutiondisplay of images disposed underneath the treated surface. Moreover, itwas observed that the slip resistance increased when the surface waswetted with water, water and detergent, and even oil.

In one aspect of the inventive subject matter, an article comprises atransparent polymeric layer having a non-abrasive microfractured firstsurface and a second surface opposite the first surface, wherein themicrofractured first surface has a structure that allows for opticalresolution of an image coupled to the second surface of equal or lessthan 1 mm. Most typically, the microfractured first surface imparts acoefficient of friction (COF) of at least 0.6.

In especially preferred aspects of the inventive subject matter, thepolymeric layer comprises a polymer film having a thickness of less than1 mm, and is preferably manufactured from a thermoplastic polymer. it isfurther generally preferred that the microfractured first surface has aplurality of micro-ablations and micro-crevices. Most typically, theoptical resolution of the image coupled to the second surface is equalor less than 0.3 mm, and/or the coefficient of friction (COF) is atleast 0.75.

It is further preferred embodiments, an image is coupled to or printedonto the second surface, and an adhesive layer may be coupled to theimage. Moreover, an elastomer may be coupled to the second surface, andan image layer and/or an adhesive layer may be disposed between thesecond surface and the elastomer. Among many other uses, it iscontemplated that the article is configured as a structured traction padfor sport equipment, a traction pad for marine use, or a traction padfor residential or public aquatic use.

Viewed from a different perspective, contemplated articles have a firstpolymer surface with a plurality of microfractures arranged in a randompattern, wherein the first surface has an average unevenness of equal orless than 0.1 mm, and wherein the article has a coefficient of friction(COF) of at least 0.6 when measured on the first surface. While notlimiting to the inventive subject matter, it is generally preferred thatthe first polymer surface is a structured surface (e.g., having a randomshape, a geometric shape (open shape like waves, or closed shape likediamonds), or having an intersecting pattern (cross-hatched, weavepattern, etc). As noted before, it is generally contemplated that themicrofractures comprise micro-ablations and/or micro-crevices. Infurther particularly preferred articles, the article has a coefficientof friction (COF) of at least 0.75 when measured on the first surface.

Consequently, the inventor also contemplates a non-abrasive articlecomprising a first polymer surface with a coefficient of friction (COF)of at least 0.6, wherein the first surface has a structure that providesincreased COF in the presence of water on the first surface relative toa persons foot contacting the first surface. Most typically, the firstpolymer surface has an average surface unevenness of equal or less than0.1 mm, and the structure comprises a plurality of microfractures. It isstill further preferred that the article is transparent and has astructure effective to allow for optical resolution of an image coupledto the second surface of equal or less than 0.5 mm.

In yet another aspect of the inventive subject matter, a method ofincreasing slip resistance of a surface of an article comprises a stepof generating a plurality of microfractures in the surface at a densitysufficient to thereby impart a coefficient of friction (COF) of at least0.6. Most preferably, the microfractures are generated by impacting thesurface with a plurality of micro-impactors to form a plurality ofmicro-ablations and micro-crevices in random orientation in the surface.

Various objects, features, aspects and advantages of the presentinvention will become more apparent from the following detaileddescription of preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWING

FIGS. 1A-1E are examples illustrating the high resolution feature ofvarious traction surfaces according to the inventive subject matter.

FIG. 2 depicts exemplary bathmats with traction surfaces andhigh-resolution images according to the inventive subject matter.

FIG. 3 schematically depicts an exemplary composite article (not toscale) with a traction surface, high-resolution image, adhesive layer,and base material according to the inventive subject matter.

FIGS. 4A-4F are scanning electron micrographs of a polymer materialbefore and after formation of the traction surface.

FIG. 5 is a photograph of one example of a composite product comprisinga traction surface according to the inventive subject matter.

FIG. 6 is a schematic illustration of another example of a compositeproduct comprising a traction surface according to the inventive subjectmatter.

DETAILED DESCRIPTION

The inventors have discovered various traction devices and methods thatovercome all or almost all of the problems associated with heretoforeknown traction devices and methods. In especially preferred aspects, theinventors have discovered that traction materials can be prepared thatare non-abrasive, have remarkably high slip resistance (especiallyrelative to a bare human foot) when the material is wet, and/or thatprovide high-resolution for images disposed underneath the surface ofthe traction device. Moreover, traction of such devices is notsignificantly reduced when detergent, or even oil is present. Suchremarkable properties are achieved by generation of microfractures in atleast one surface of the traction device, typically in randomorientation and at an average size less than 1 mm, wherein that surfacemay or may not be structured.

Thus, in especially preferred aspects of the inventive subject matter, atraction device has a transparent polymeric layer having a non-abrasivemicrofractured first surface and a second surface opposite the firstsurface, wherein the microfractured first surface has a structureeffective to allow for optical resolution of an image coupled to thesecond surface of equal or less than 1 mm, and more typically equal orless than 0.5 mm, and most typically equal or less than 0.25 mm, andwherein the microfractured first surface imparts a coefficient offriction (COF) of at least 0.6. Viewed from a different perspective, atraction device has a polymer surface with a plurality of microfracturesarranged in a random pattern therein, wherein the first surface has anaverage unevenness of equal or less than 1.0 mm, more typically equal orless than 0.5 mm, and most typically equal or less than 0.1 mm, andwherein the article has a coefficient of friction (COF) of at least 0.6when measured on the first surface. Due to the specific surfacestructure of the traction device, it therefore also contemplated thatthe device is or comprises a non-abrasive article having a polymersurface with a coefficient of friction (COF) of at least 0.6, whereinthe surface has a structure that provides increased COF in the presenceof water on the surface (especially relative to a persons footcontacting the first surface).

While not wishing to be bound by any theory or hypothesis, it iscontemplated that the microfractures, and especially the edges ofmicro-depressions, micro-ablations, and/or micro-crevices will not onlyprovide in their totality a significant quantity of relatively sharp butnon-abrasive engagement surfaces, but also help in disruption of acontinuous water or other fluid film that would otherwise form alow-traction layer. Thus, it should be appreciated that slip resistanceof a surface of an article can be increased by generating a plurality ofmicrofractures in the surface, most preferably at a density sufficientto impart a coefficient of friction (COF) of at least 0.6, morepreferably at least 0.65. Unless stated otherwise, all COF values arebased on determination using the test protocol suitable for analysiswith a Brungraber MkII PIAST (Portable Inclinable Articulated StrutTribometer; following ASTM F1677) and/or for analysis with an English XLVIT Tribometer (following ASTM F1679). Alternative COF measures can beobtained using the Tortus Model Mk 2 (following AS/NZS 4586: 2004 Slipresistance classification of new pedestrian surface materials).

As used herein, the term “microfracture” in a surface refers to adiscontinuity in a portion of the surface such that an edge is createdin the surface. In most cases, discontinuity can be characterized as amicro-ablation (e.g., flaking off of a portion of the surface withconcomitant creation of an edge) a micro-crevice (e.g., tear or breakageextending into the material with microfractures with concomitantcreation of an edge), and/or a micro-depression (e.g., localized impactarea generated by localized compaction of the material withmicrofractures with concomitant creation of an edge). Typically, themicrofractures will not extend across the material, but will be limitedto the surface. In most cases, the average depth of a microfracture willbe less than 0.1 mm, more typically less than 0.07 mm, and most lessthan 0.05 mm.

As further used herein, the term “surface unevenness” refers tocharacter of the surface not taking into account the unevenness createdby the microfractures. For example, surface unevenness may be due to themanner of manufacture of the material or may be intentionally generated(e.g., by stamping, hot-pressing, etc.) prior to generation of themicrofractures. Among other things, surface unevenness may have a shapeof a random pattern (e.g., waves, hills-and-valleys, etc., which may bepresent in repeating units) or may have a regular pattern. Thus, surfaceunevenness may be part of an intentionally generated structured surface,wherein the structured surface may have random shape (e.g., similar tocathedral glass), a geometric shape (e.g., open shapes like waves, orclosed shapes like honeycomb or diamond patterns), and/or intersectingpatterns (cross-hatched patterns, weave patterns, etc). Therefore, inmost cases, the average surface unevenness will be equal or less than 5mm, more typically equal or less than 2.5 mm, even more typically equalor less than 1.0 mm, and most typically equal or less than 0.5 mm (e.g.,less than 0.3 mm, or less than 0.1 mm).

As still further used herein, the term “non-abrasive” in conjunctionwith the surfaces presented herein is intended to express that thesurfaces are non-abrasive to human skin under ordinary conditions. Forexample, a surface is considered non-abrasive when the surface can bemoved at a speed of 1 foot per second across human skin (e.g., forearm)at a contact force of 50N without causing injury or severe irritation.

As also used herein, the term “optical resolution of an image” refers tothe ability to perceive with the unaided eye two distinct lines (orother image elements) on the image as two distinct lines (or other imageelements) when viewed through the microfractured surface, wherein thedistance between the two lines (or other image elements) is specified inmillimeters. In most aspects, the layer and the microfractured firstsurface will have a structure effective to allow for optical resolutionof an image coupled to the second surface of equal or greater than 0.01mm, and more typically equal or greater than 0.05 (and in some casesequal or greater than 0.1 mm), but equal or less than 1 mm, and moretypically equal or less than 0.5 mm. Thus, it should be noted that theterm “equal or less than” in conjunction with a specified distance doesnot include distances that can not be resolved by the human unaided eye.

In particularly desirable aspects, contemplated devices can be readilymodified by applying a print or other colored material to the materialon a surface opposite the surface having the microfractures. Prints maybe applied directly by printing on the surface or by contacting thesurface with a printed material. Alternatively, any other material canalso be applied to the surface (e.g., reflective paint or reflectivetape, newspaper clippings, plant materials, sand, sea shells, etc.),preferably (but not necessarily) by use of an adhesive. Similarly, it isalso contemplated that a user may paint or draw a picture onto thesurface. Thus, it should be appreciated that the image or otherdecorative item on the device is protected from moisture, abrasion, andother environmental influences by the microfractured surface andunderlying material. It should therefore be appreciated thatcontemplated devices may be configured into any device or article thatwould benefit from a surface with increased slip reduction. For example,suitable devices or articles may include traction pads and surfaces formarine use, sport equipment, commercial safety equipment, and/orresidential or public aquatic use. Thus, and among many other examples,devices and articles may be configured as (optionally adhesive) mats,strips, or laminated products (e.g., laminated to EVA polymer or othersoft or shock-absorbing material). Most typically, contemplated devicesand articles will further include a pressure sensitive adhesive tofacilitate application and removal of the device. Remarkably, it shouldbe noted that the traction between the microfractured surface and ananimate (e.g., foot or hand of a person) or inanimate object increaseswhen water is disposed between the first surface and the object. As afurther consequence of the microfractures, it should also be appreciatedthat now traction articles can be manufactured with heretoforeunachieved optical qualities.

FIGS. 1A-1E exemplarily illustrate the remarkable resolution capabilityof traction surfaces according to the inventive subject matter. Forexample, FIG. 1A is a photograph of a slide ruler that is partiallycovered by a polycarbonate film, wherein the side contacting thefingertips is treated to have microfractures and wherein the oppositeside is untreated. The edge of the film extending from the left side ofthe image towards the 28.5 cm mark is shown by the arrows. As is readilyapparent, ruler markings are visible with remarkable sharpness and highclarity. FIGS. 1B-1E are photographs of segments of the resolution barfrom the IOS 12233 Resolution Measurement Chart (that was printed onto11×17) at approximately 2-fold magnification. As is readily apparentfrom the images, the optical resolution of the image disposed underneaththe traction surface was well below 0.5 mm. In most cases, and furtherdepending on the particular material and treatment, optical resolutioncan be achieved as low 0.5 mm, typically as low as 0.4 mm, moretypically as low as 0.3 mm, and even as low as 0.2 mm (or even lower).Such high optical resolution is entirely unexpected, especially wherethe surface provides a high coefficient of traction (e.g., COF of atleast 0.45, more typically at least 0.5, even more typically at least0.6, and most typically at least 0.65).

Thus, fraction surfaces and devices can be produced in an visuallyattractive manner while providing substantial increase in slipresistance. Exemplary embodiments are depicted in FIG. 2, wherehigh-resolution bathmats are shown. Devices prepared according to theinventive subject matter (typically comprising one or more polymersheets, which may or may not be the same polymer material) will be diecut to specification for use in a particular surface, for example, asurfboard, bathtub or boat deck to provide a non-slip traction surfaceand to provide a desired design pattern on the surfboard, bathtub orboat deck. The so formed device typically comprises a thin sheet of apolymer (e.g., polycarbonate or acrylic polymer) and apressure-sensitive adhesive layer on one surface. Most preferably, aremovable protective layer covers the pressure-sensitive adhesive layer,while the other surface of the device incorporates an engineeredmicrostructure that is formed on the surface to so provide the non-sliptraction surface when the surface is wet or dry.

FIG. 3 schematically illustrates a typical example of a traction deviceaccording to the inventive subject matter where composite article 300comprises a polymer film 302 having microfractured first surface 302A.An image layer 304 is disposed on the surface that is opposite themicrofractured first surface 302A wherein the image layer may bedirectly printed on the surface or glued (or otherwise affixed) to thesurface. Coupling of the polymer film and image to another material 308(e.g., elastomer, floor elements (wood, tile, etc.)) is preferablyachieved via pressure sensitive adhesive 306. However, it should benoted that the particular nature of the manner of coupling is notcritical to the inventive subject matter. For example, microfracturedfirst surface 302A may be formed directly on the material 308. Thus, itshould be appreciated that the image layer and/or the adhesive 306 maybe omitted.

In one especially preferred example, contemplated devices can bemanufactured from a thin sheet of a polymeric material (e.g.,thermoplastic), and most preferably a polycarbonate or an acrylatepolymer film having a thickness of about from 0.05 inch to 0.01 inch. Ofcourse, it should be noted that the film can be clear and transparent,colored and transparent, or translucent. Moreover, it is generallypreferred that at least one side of the film has a smooth surface ontowhich an image (or other decorative or functional item) can be printedor otherwise positioned (e.g., a graphic, a logo, or photograph,reflective material, typically using silk screening, inkjet printingequipment, or stickers). Instead of pictures, it should be appreciatedthat various (preferably generally flat) objects or layers with objects,etc. may also be coupled to the smooth surface. Similarly, it ispreferred that the opposite (top) surface of the film is also smooth,however, in at least some circumstances, the opposite surface may alsobe non-smooth or processed to be non-smooth (e.g., squares, grooves,matt finish, or various embossed patterns/logos) using various toolswell known in the art (e.g., die press, roller press, stamps, etc.).

Depending on the particular use and treatment, it is contemplated thatthe thickness of the film may vary considerably, and that numerousthicknesses are deemed suitable for use herein. For example, where thefilm is placed onto an article as a decorative anti-slip device,suitable film thickness may be between 0.025 mm and 2 mm, and morepreferably between 0.1 mm and 0.5 mm. On the other hand, where the filmis used as a structural component, the thickness may be between 0.5 mmand 5 cm (and even more), and more typically between 1 mm and 2 cm. Ofcourse, and as noted before, it should be appreciated thatmicrofractures may also be imparted into an already present surfacewithout addition of a film using the methods as presented below. Suchuse may be especially advantageous in an environment where a film neednot be replaced or where the surface has an irregular shape that wouldbe difficult to cover with a film.

It should be appreciated that while polycarbonate and acrylic polymerfilms are typically preferred, numerous alternative polymers are alsodeemed suitable and especially include numerous thermoplastics (infra),biodegradable plastics (e.g., starch-based polymers, polylactates,polyhydroxybutyrates, etc.), and so on. Thus, and viewed from adifferent perspective, suitable polymers include various acrylics,polyesters, polyamides, silicones, polyurethanes, etc., and allreasonable mixtures thereof.

Among other suitable choices, contemplated thermoplastics includeacrylonitrile butadiene styrene (ABS), acrylic (PMMA), celluloid,cellulose acetate, cyclic olefin copolymer (COC), ethylene-vinyl acetate(EVA), fluoroplastics (PTFE, alongside with FEP, PFA, CTFE, ECTFE,ETFE), liquid crystal polymer (LCP), polyacetal (POM or Acetal),polyacrylates (Acrylic), polyacrylonitrile (PAN or Acrylonitrile),polyamide (PA or Nylon), polyamide-imide (PAI), polybutyleneterephthalate (PBT), polycaprolactone (PCL), polyethylene terephthalate(PET), polycarbonate (PC), polyhydroxyalkanoates (PHAs), polyketone(PK), polyesters, polyethylene (PE), polyethersulfone (PES), polyimide(PI), polylactic acid (PLA), polypropylene (PP), polystyrene (PS),polysulfone (PSU), polyurethane (PU), Polyvinyl acetate (PVA), polyvinylchloride (PVC), polyvinylidene chloride (PVDC), andstyrene-acrylonitrile (SAN).

Where the polymeric film is part of a composite structure (e.g., tailpad for surfboard, padded bathmat, etc.), it is especially preferredthat the polymeric film is attached (typically via adhesive) to anelastomer. Suitable elastomers include natural rubber (NR), syntheticpolyisoprene (IR), butyl rubber (copolymer of isobutylene and isoprene,IIR), halogenated butyl rubbers (chloro butyl rubber: CIIR; bromo butylrubber: BIIR), polybutadiene (BR), styrene-butadiene Rubber (copolymerof polystyrene and polybutadiene, SBR), nitrile rubber (copolymer ofpolybutadiene and acrylonitrile, NBR), hydrogenated nitrile rubbers(HNBR), chloroprene rubber (CR), polychloroprene, neoprene, bayprenetc., EPM (ethylene propylene rubber, a copolymer of ethylene andpropylene) and EPDM rubber (ethylene propylene diene rubber, aterpolymer of ethylene, propylene and a diene-component), polyacrylicrubber (ACM, ABR), silicone rubber (SI, VMQ), fluorosilicone rubber(FVMQ), fluoroelastomers (FKM, and FEPM), polyether block amides (PEBA),chlorosulfonated polyethylene (CSM), (Hypalon), and ethylene-vinylacetate (EVA). Of course, it should be appreciated that the actualmaterial need not be limited to elastomers, and that all alternativematerials are also deemed suitable for use herein (e.g., metal, metalalloys, ceramics, wood, etc.).

While it is generally preferred that the material onto which themicrofractures are formed is or comprises a polymer film, it should beappreciated that the microfractures can be generated on numerous othershapes include cylinders, spherical shapes, and irregularly shapedobjects. Indeed, all shapes are deemed appropriate so long as suchshapes allow generation of a micro-structured surface. Thus, thethickness of the films is not limiting to the inventive subject matter,and suitable films may have a thickness of between 10-100 micrometer,between 100-300 micrometer, between 300-1000 micrometer, and eventhicker. It should be further especially noted that pre-existingsurfaces may also be treated with the methods disclosed herein to sogenerate the traction surface (e.g., polymeric boat deck or surfboard isblasted with grit as described above). Thus, contemplated methods allowmanufacture of not only temporary traction surfaces by applying suchfilms, but also allow permanent modification of existing surfaces toincrease fraction.

It is further preferred that the bottom surface of film includes apressure sensitive adhesive layer (typically on top of the image orother graphic material) to ensure permanent or semi-permanent adhesionof the bottom surface of the film to the surface on which a non-sliptraction surface is desired. Of course, numerous alternative adhesivesare also deemed suitable and all known adhesives and adhesivecompositions are considered appropriate for use herein. Where desired orneeded, a removable sheet material is added on the bottom surface of theadhesive layer (e.g., paper or other type sheet material) to protect theadhesive layer prior to use so that the adhesive layer along with thenon-slip traction film may be transported to the surface where thenon-slip traction pad is needed. Of course, it should be recognized thatthe traction devices described herein may be shaped to any final formvia all known manners (e.g., die cut using a stamping die).

In especially preferred aspects of the inventive subject matter, themicro-structured friction surface is created in a (typicallynon-ablative) micro-impaction process. In a particularly preferredexample, abrasive cleaning/sandblasting equipment and metal oxide gritis used, typically using direct pressure and siphon feed systems. Amongother suitable choices, the preferred impact medium is commerciallyavailable aluminum oxide grit, typically with primary grit sizes of #60,#70, #80, #90, and/or #100. Other suitable aluminum oxide grit sizesinclude those from a macro grit #8 on the large end to a small grit #220on the fine end. Under many conditions, such sizes will produce amicro-structured surface with significantly enhanced friction.

Most significant process parameters for devices contemplated herein arethe air pressure used to convey the media, the size of grit used, andthe distance from which the grit is sprayed onto the film. The followingTables 1 and 2 exemplarily illustrate sizes of grits used herein wherethe grit was delivered to the film at a pressure of between 25-100 psigat a distance of between about 1 inch to about 6 feet.

TABLE 1 Inches Microns Mini- Mini- Macro Grit Average Maximum mumAverage Maximum mum # 60 0.010 0.0160 0.0065 254 406 165 # 70 0.0080.0130 0.0050 203 330 127 # 80 0.0065 0.0115 0.0040 165 292 102 # 900.0057 0.0095 0.0350 145 241 89 # 100  0.0048 0.0080 0.0025 122 203 63

TABLE 2 Inches Microns Mini- Mini- Macro Grit Average Maximum mumAverage Maximum mum # 36 0.019 0.030 0.012 483 762 305 # 46 0.014 0.0220.0095 356 559 241 # 54 0.012 0.0195 0.0080 305 495 203

It should further be appreciated that the grit material need not belimited to aluminum oxide, but may also include various silicates andother minerals, metals, and metal oxides, and all reasonablecombinations thereof. Where thermal issues are encountered, frozen CO2grit may be employed. Likewise, the pressure to deliver the grit to thesurface to be treated may vary considerably, and suitable pressures willtypically lie in the range of 10-500 psig, and more typically between20-80 psig at a distance between the nozzle and polymer surface ofbetween 0.1 inch and several feet, and more typically 10-50 inches.Suitable pressures may be determined by the person of ordinary skill inthe art without undue experimentation.

Furthermore, it should be noted that where contemplated treatmentprocesses produce excessive or undesirable heat in the treated material,the material can be cooled on a cooling table or other surface,typically to a temperature of 60° C. and below. Alternatively, solid CO2grit may also be employed for temperature control. On the other hand, itshould also be noted that (pre-)heating of the surface that is to betreated may be advantageous, especially where the material is athermoplastic material. Such preheating may advantageously allowreduction of pressure or allow for modification of the so generatedmicrofractured surface.

Regardless of the manner of grit delivery, it is generally preferredthat the microfractured surface is produced in a non-ablative manner.Thus, the loss of material (on a weight basis) in non-ablativemicrofracturing after grit delivery and formation of the microfracturesis preferably less than 15%, more preferably less than 10%, even morepreferably less than 5%, and most preferably less than 3%. Thus, andviewed from a different perspective, preferred methods of manufactureproduce a surface with microfractures by local impaction and/ordensification of the surface.

In still further alternative methods, the microfractured surface mayalso be prepared using different manufacture processes, and especiallypreferred processes include stamping (e.g., using a roller or a diehaving a micro-structured surface). Alternatively, various ablativemethods are also deemed suitable for use herein, and especiallypreferred alternative methods include laser- or ultrasound-basedmicro-ablation, and dissolution of a dissolvable phase in the surfacethat is to be treated. Such dissolution is preferably performed using asolvent in a process similar to chemical etching. Alternatively, aphotolithographic process may be employed to produce the microfracturedsurface, and it yet further contemplated aspects, heat treatment of thesurface is contemplated where the surface comprises a plurality ofmicro-structured thermolabile elements. In still further contemplatedalternative methods, the surface may be pretreated with an ultra-coldmedium (e.g., liquid nitrogen) and then impacted with a roller, die, orgrit.

FIGS. 4A-4F depict scanning electron micrographs of sections of apolycarbonate film before and after treatment with metal oxide grit.More particularly, FIG. 4A is an SEM image of a treated surface at100-fold magnification showing numerous micro-crevices andmicro-ablations. FIG. 4B depicts the same material at 100-foldmagnification before treatment. As is readily apparent, nomicrofractures are present. It should also be noted that the treatedsurface of the polycarbonate film of FIGS. 4A-F also had a randomstructured surface (see especially FIG. 4F), and that the averagesurface unevenness was substantially not affected by the microfractures.FIGS. 4C and 4D provide a 45 degree angled view of the treated anduntreated surfaces, respectively, at 100-fold magnification. Once more,it is readily apparent that the micro-ablations, micro-crevices, andmicro-depressions in their totality provide a large measure ofengagement ridges that are not found in the untreated surface.

FIGS. 4E and 4F show cross sectional views at 200-fold magnification oftreated and untreated films, respectively. Once more, the differencebetween treated and untreated surface it is readily apparent. It shouldbe appreciated that the average surface unevenness on the treated side(was due to the random structuring of the starting material) wassubstantially unaffected, but that the plurality of micro-fracturesprovide a plethora of engagement ridges. In most cases, the averagelength of micro-fractures is between 0.02 and 0.4 mm, and more typicallybetween 0.05 and 0.3 mm. Similarly, the average area of a micro-ablationand/or micro-depression is between 1 and 0.5 μm², and more typicallybetween 5 and 0.2 μm². The average depth of the microfractures istypically between 0.5 and 50 μm, more typically between 1 and 30 μm, andmost typically between 1 and 10 μm.

Films with thusly prepared surfaces will be particularly useful toimpart anti-slip or increased traction to various articles ofmanufacture, and FIG. 5 depicts one exemplary tail pad 500 for a surfboard in which a shaped EVA elastomer portion 520 is partially coveredby traction surface 510. In another example, as depicted in FIG. 6, asafety step 600 is formed from a hard rubber base 610 with alongitudinal channel 612. Traction film 620 is coupled to the base 610,typically via an adhesive (not shown). Additional adhesive can be usedto adhere step 600 to floor 640 (e.g., concrete floor).

EXAMPLES

The following examples are provided as representative (but notexhaustive) methods and results for improved traction surfaces. Allmaterials below are based on an acrylic film or a polycarbonate filmhaving one random structured surface and an opposing smooth surface.Tests were conducted in accredited testing facilities according toindustry standard protocols as described in more detail below.Microfractures were imparted into one side of the film by impaction withaluminum oxide grit #80 at a pressure of 20-80 psig at a distance ofabout 3 feet.

US ASTM Dry Friction Rating: Samples were prepared and mounted accordingto code and tribometer manufacturer's instructions. The test protocolfor analysis with the Brungraber Tribometer followed ASTM F1677, and thetest protocol for analysis with the English Tribometer followed ASTMF1679. The mean results for both tests were 0.68. Classification range0-0.7

Dry Floor Friction Testing and Rating: A sample was mounted to a1200×600×12 mm particle board for testing. The sample was washed with apH neutral detergent, rinsed with tap water and dried. The test protocolfor analysis with the Tortus Floor Friction Tester followed AS/NZS 4586:2004 Slip resistance classification of new pedestrian surface materialsusing a Tortus Floor Friction Tester. Equipment used was a Tortus ModelMk 2 with Slider 96 (Four S). The mean value of 2 independent tests(rounded to 0.05) was 0.80 (COF). Classification ranges F>0.4; G<0.4;the surface was thus classified as category F.

Wet slip resistance: Wet slip resistance testing used the wet pendulummethod. A sample was mounted to a 1200×600×12 mm particle board fortesting, and the sample was washed with a pH neutral detergent, rinsedwith tap water and dried. Test standard was AS/NZS 4586: 2004 Slipresistance classification of new pedestrian surface materials using aStanley Skid Resistance Tester (Pendulum) with Slider 96 (Four S). themean value of 5 independent tests was 57 (expressed as BPN).Classification ranges V>54; W 45-54 X 35-44; y 25-34; Z<25; the surfacewas thus classified as category V.

Oil-Wet Ramp: A sample was mounted to a 1200×600×12 mm particle boardfor testing, and the sample was washed with a pH neutral detergent,rinsed with tap water and dried. Test standard was AS/NZS 4586-2004 Slipresistance classification of new pedestrian surface materials usingstandard ramps. The mean overall acceptance angle was determined to be22.4°; Classification ranges 6° to 10°: R9; Over 10° to 19° : R10; Over19° to 27°: R11; Over 27° to 35°: R12; Over 35°: R13; the surface wasthus classified as category R11.

Wet/Barefoot Ramp: Sample preparation substantially similar to that foroil wet ramp above; Test standard was AS/NZS 4586:2004 Slip resistanceclassification of new pedestrian surface materials. The mean angle ofinclination was determined to be 21°; the surface was classified ascategory B.

Surfaces with moderate microfracturization (e.g., used in bathmats)provided the following results in comparison with a terrazzo tilesample:

Brungraber Mark III Testing: Test protocol followed ASTM F-1677 testmethod under both dry and wet conditions. Configuration of theBrungraber Mark III in direction of travel: north (n), east (e), south(s), west (w). Terrazzo Tile Sample without traction surface: Dryresults 0.76 (n), 0.76 (w); average=0.76; Wet: 0.13 (n), 0.13 (w);average=0.13; Terrazzo with traction surface: Dry: 0.87(n), 0.88 (w);average=0.88; Wet: 0.41 (n), 0.32 (w) 0.35 (s); average=0.36.

English XL Testing: Test protocol followed ASTM F-1679 test method underboth dry and wet conditions. The following slip test results wereobtained using the English XL Variable Incidence Tribometer.Configuration of the English XL in direction of travel: north (n), east(e), south (s), west (w). Terrazzo Tile Sample without traction surface:Dry: not recorded, Wet: 0.30 (n); Terrazzo with traction surface: Dry:1.0 (n), Wet: 0.66 (n), 0.70 (w); average=0.68.

Thus, specific embodiments and applications of methods of tractionsurfaces and methods therefor have been disclosed. It should beapparent, however, to those skilled in the art that many moremodifications besides those already described are possible withoutdeparting from the inventive concepts herein. The inventive subjectmatter, therefore, is not to be restricted except in the spirit of theappended claims.

1. An article comprising: a transparent polymeric layer having anon-abrasive microfractured first surface and a second surface oppositethe first surface; wherein the layer and the microfractured firstsurface have a structure effective to allow for optical resolution of animage coupled to the second surface of equal or less than 1 mm; andwherein the microfractured first surface imparts a coefficient offriction (COF) of at least 0.6.
 2. The article of claim 1 wherein thepolymeric layer comprises a polymer film having a thickness of less than1 mm.
 3. The article of claim 1 wherein the polymeric layer comprises athermoplastic polymer.
 4. The article of claim 1 wherein themicrofractured first surface has a plurality of micro-ablations andmicro-crevices.
 5. The article of claim 1 wherein the optical resolutionof the image coupled to the second surface is equal or less than 0.3 mm.6. The article of claim 1 wherein the coefficient of friction (COF) isat least 0.65.
 7. The article of claim 1 wherein an image is coupled toor printed onto the second surface, and optionally an adhesive layercoupled to the image.
 8. The article of claim 1 further comprising anelastomer coupled to the second surface, and optionally at least one ofan image layer and an adhesive layer disposed between the second surfaceand the elastomer.
 9. The article of claim 8 configured as a structuredtraction pad for sport equipment.
 10. The article of claim 1 configuredas a traction pad for marine use, or a traction pad for residential orpublic aquatic use.
 11. An article having a first polymer surface with aplurality of microfractures arranged in a random pattern, wherein thefirst surface has an average unevenness of equal or less than 0.1 mm,and wherein the article has a coefficient of friction (COF) of at least0.6 when measured on the first surface.
 12. The article of claim 11wherein the first polymer surface is a structured surface.
 13. Thearticle of claim 11 wherein the structured surface has a shape selectedfrom the group consisting of an random shape, a geometric shape, and anintersecting pattern.
 14. The article of claim 11 wherein themicrofractures comprise micro-ablations and micro-crevices.
 15. Thearticle of claim 14 wherein the article has a coefficient of friction(COF) of at least 0.65 when measured on the first surface.
 16. Anon-abrasive article comprising a first polymer surface with acoefficient of friction (COF) of at least 0.6, wherein the first surfacehas a structure that provides increased COF in the presence of water onthe first surface relative to a persons foot contacting the firstsurface.
 17. The article of claim 16 wherein the first polymer surfacehas an average surface unevenness of equal or less than 0.1 mm, andwherein the structure comprises a plurality of microfractures.
 18. Thearticle of claim 16 wherein the article is transparent and has astructure effective to allow for optical resolution of an image coupledto the second surface of equal or less than 0.5 mm.
 19. A method ofincreasing slip resistance of a surface of an article, comprising:generating a plurality of microfractures in the surface at a densitysufficient to thereby impart a coefficient of friction (COF) of at least0.6.
 20. The method of claim 19 wherein the step of generating themicrofractures comprises impacting the surface with a plurality ofmicro-impactors to form a plurality of micro-ablations andmicro-crevices in random orientation in the surface.